Development of Compressor Backside Flow Analysis Method Using One-Dimensional Leak Model

Abstract

Recently, turbochargers are required to improve automotive engine performance, so the turbocharger efficiency has become important. The turbocharger efficiency is determined by compressor efficiency, turbine efficiency, heat loss, and mechanical loss. Therefore, it is very important to understand the compressor thrust force which causes mechanical loss. For this purpose, CFD analysis with the compressor backside cavity is a very useful method. Since the internal flow in the backside cavity depends on the leak flow rate from the piston ring, it is necessary to define the leak flow rate accurately for the CFD boundary condition. However, there are few studies on CFD with backside cavity considering leak flow rate. In this study, the model of leak flow from the piston ring is developed using one-dimensional performance prediction. The method is based on nozzle flow with the continuity equation in a steady-state adiabatic condition, and it is applied to the calculation of boundary condition for the piston ring. Finally, the static pressure distribution of the compressor backside cavity is investigated by pressure transducers, and it is compared to CFD analysis. The CFD results with this technique show good agreement with the measured data, leading to an accurate estimation of compressor thrust force.